1. Field of the Invention
The present invention relates to a portable terminal having a ground unit that is capable of minimizing interference between electromagnetic waves generated from the portable terminal and a hearing aid.
2. Description of Related Art
Portable terminals are easily carried devices that have one or more of functions such as supporting voice calls and other telephony functions, inputting and/or outputting information, storing data and the like. As the portable terminals become multi-functional, they incorporate additional functions, such as capturing still images or moving images, playing music or video files, playing games, receiving broadcasts, and the like, thereby providing integrated multimedia devices.
Currently, users are increasingly interested in effects of the electromagnetic waves generated from the portable terminal on the human body. In particular, people who use hearing aids are increasingly interested minimizing malfunctions of the hearing aid caused by the electromagnetic waves generated from the portable terminal interfering with the operation of the hearing aid when using the portable terminal.
Accordingly, manufacturers of hearing aids and other wireless devices are required to meet the Federal Communications Commission (FCC) requirements for hearing aid compatibility (HAC) in the United States. Such requirements have also spread throughout the world. The HAC serves to authenticate and evaluate compatibility of hearing aids and portable terminals such that the hearing aids and the portable terminals may be simultaneously used without too much interference therebetween. Generally, the electromagnetic waves generated from a portable terminal are sensed and amplified by a telecoil (i.e., T-coil) of a hearing aid, and thus call sound is transmitted to the hearing aid user. The HAC specifies a method for measuring a magnetic response of the hearing aid and providing a standard value thereof.
One measuring method of the HAC, as shown in FIG. 1, measures the amount of the electromagnetic waves generated at the periphery of a receiver of the portable terminal. The portable terminal includes a first body 10, and a second body 20 coupled to the first body 10 to be foldable or unfoldable therewith by pivoting the first body 10 with respect to the second body 20.
A receiver 11 is provided at one end of the first body 10, and a measuring region 12 having a size of 5(cm)×5(cm) centering on the receiver 11 and having a height of 1(cm) from the surface of the terminal is specified. The measuring region 12 is divided into nine grids total, one of which is a central grid 14, the remaining eight are border grids 13. Measurements of the value of electromagnetic waves emitted from each of the grids 13, 14 are taken by an electromagnetic wave measuring probe. The values of three of the eight border grids 13 emitting the greatest amount of electromagnetic waves are excluded from values of the eight border grids 13 surrounding the central grid 14. The HAC requires that the greatest value among values of the electromagnetic waves from the central grid 14 and the remaining five border grids 13 should be below a predetermined reference value.
Accordingly, various attempts have been made to design and fabricate portable terminals that meet the above requirements and reduce the amount of electromagnetic waves generated from the periphery of the receiver of the portable terminal.